The present invention relates to a combustor that is a component of a gas turbine, more particularly, relates to a transition piece for transferring a working fluid having been burnt to an annular flow path of a gas turbine through a cylindrical liner and a repair method therefor.
As a method for repairing a transition piece of a combustor, a method in which cracks are repaired and residual stress is relieved and wear resistance is improved by combining shot peening and solution heat treatment has been known and has been disclosed in JP-A-6-288549 specification, for example.
However, it has been demanded that the above-described prior art be improved more to achieve high efficiency for energy saving, increased strength and prolonged service life of an outlet portion of combustor, and decreased repair and inspection manpower.
An object of the present invention is to achieve energy saving, increased strength, prolonged service life, and decreased repair and inspection manpower while facilitating the replacement and repair of a transition piece of a combustor.
To attain the above object, the present invention provides a gas turbine comprising a compressor for compressing air as a working fluid, a combustor for producing combustion gas by mixing fuel with the compressed air, and a turbine for generating a rotational power at the time of expansion of the combustion gas, and further comprising a cylindrical liner; a transition piece for transferring the working fluid from the liner to the turbine; an outlet portion of the transition piece, which has a region parallel with the direction of rotating shaft of the turbine; cooling holes formed in the region so that the longitudinal intervals thereof are lengthened; and a picture frame portion provided to secure stiffness near the outlet of the outlet portion.
Also, the present invention provides a repair method for a gas turbine having a compressor for compressing air as a working fluid, a combustor for producing combustion gas by mixing fuel with the compressed air, and a turbine for generating a rotational power at the time of expansion of the combustion gas, comprising providing, at an outlet portion of a transition piece for transferring the working fluid to the turbine, a region parallel with the direction of rotating shaft of the turbine, cooling holes formed in the region so that the longitudinal intervals thereof are lengthened, and a picture frame portion to secure stiffness near the outlet of the outlet portion; cutting the outlet portion in a portion where the longitudinal intervals of the cooling holes are lengthened and separating the picture frame portion, and welding a picture frame portion prepared in advance in the cut portion for replacement.
Further, in the repair method described above, it is preferable that deterioration in the cut portion be evaluated, and the surface temperature state of the outlet portion be estimated, whereby the arrangement of the cooling holes be determined.
Further, in the repair method described above, the picture frame portion prepared in advance is preferably another picture frame portion that has been repaired and is reused.
Further, in the repair method described above, the length of the whole of the transition piece is preferably adjusted by grinding the end face of the cut-off picture frame portion.
Further, in the repair method described above, the picture frame portion is preferably welded to the cut portion via a connecting member.
Further, in the gas turbine described above, the picture frame portion is preferably welded via a connecting member formed with cooling holes.